Support devices are well known for supporting elements to be supported, in particular the bodies of patients who are confined to bed or have to be kept still for prolonged periods, in which case such devices are generally mainly known as mattresses. It is also well known that confining such patients to bed or keeping them still for prolonged periods leads to complications, in particular bedsores.
Therefore, in the prior art, various devices have been proposed for distributing the weight of the patient over an interface body area in contact with the support device that is as large as possible so as to keep the interface pressures below pressures at which capillaries become occluded, or even, in therapeutic devices, so as to stimulate re-vascularization of tissue.
For example, Document FR-A-2 707 874 discloses a mattress designed in particular to prevent decubitus ulcers and provides at least one closed or controlled-release flexible chamber that is inflatable under a pressure that is a function of the maximum penetration distance to which the element to be supported is allowed to penetrate into the support element, the penetration distance being designed to be set and to be approximately in the range 12 cm to 17 cm. That prior document therefore makes provision for the filling or emptying means to be servo-controlled so as to fill or to deflate said chamber until the extent of penetration is brought to approximately the set penetration distance. The penetration distance is measured by means of a capacitive device referenced 9, 10 which can be seen clearly in FIGS. 1 and 4 of Document FR-A-2 707 874.
Furthermore, in Document FR-A-2 718 347=EP-A-676 158 the Applicant describes a method and a system for supporting an element to be supported, in particular the body of a patient, making it possible to support the element at an essentially constant controlled penetration depth by using a measurement device for measuring the penetration distance, the measurement means differing from those of the preceding document by the fact that they comprise a metal element in the form of a thin film placed in the vicinity of the top face of the support element and combined with an inductive device forming a position detector secured to the bottom face of the support element. Similarly, provision is made to servo-control filling or deflating the chamber of the support element so as to achieve the pre-set penetration distance regardless of the weight of the element to be supported, in particular the body of a patient.
For most patients, the prior art solutions offer a good weight/body area ratio, i.e. they distribute well the weight of the patient over the support device, but they suffer from the drawback of not systematically bringing the penetration of the body of every patient accurately to a level of natural equilibrium that procures the ideal weight/body area distribution ratio.